Extended historys with 1 minute RRAs. Math and file size.

[Temujin]

Hello all. I'm an old MRTG user fan and am converting to Cacti over RRD on RHEL4. I have to say, I'm extremely pleased with the flexibility of the product. I have a quick question on RRAs. I'm polling right now using CACTID with a 1 minute interval based on the following thread:

http://forums.cacti.net/about7504-0-asc-15.html

This is mostly just to understand the product. It's working like a charm. I've been able to work my way thru the forums to understand most of my questions. Now i'm at a stumbling point.

I'm hitting about 20 devices right now of various vendor lineage. Cisco R&S, PIX, Nokia, CheckPoint, Teros, F5 etc. I'm pulling multiple data sources per node. My server is doing fine. I'm going to grow this (carefully) to about 100 to 150 nodes over the next 3 months. I plan on being a CACTID thruput guenea pig for one of the other threads on that subject. Before I get too deep in my buildout, I'm probably going to start from scratch with an overlapping server and rebuild all the RRAs and up from the ground up to suit my needs.

Concerns/Issues/Questions:

1. I'm still having trouble with RRA building. I think I have it down pat but I would love to have someone look at my numbers to validate them and also I'd love to hear comments on digging this thuroughly into long term graphs.

My math:

1 day = 1440 minutes
1 week = 10080 minutes
1 month = 40320 minutes
1 quarter = 120960 minutes
1 year = 483840 minutes
5 years = 2419200 minutes
10 years = 4838400 minutes

Steps Rows Timespan
Hourly (1 minute avg) - 1 year 1 60 483840
Daily (1 minute avg) - 1 year 1 86400 31104000
Weekly (5 minute avg) - 5 years 5 2016 483840
Monthly (5 minute avg) - 5 years 5 8064 483840
Quarterly (15 minute avg) - 5 years 15 8064 161280
Yearly (15 minute avg) - 10 years 15 32256 322560

This is what I plan on building on. One of the things I can't figure out how to guestimate is the actual size of each RRA that will be spun off of this. Anyone care to comment?

Also, is there a way to manipulate the order in which graphs are presented in the HTML pages?

Thanks for listening everyone.

[gandalf]

Here's a snipped from my post at http://forums.cacti.net/viewtopic.php?t=9605

Code: Select all

Space allocation with rrdtool
The space needed is calculated from


    * the number of data sources needed (e.g. traffic in and traffic out form two data sources)
    * the number of rra's needed (e.g. one archive for storing original data points, a second one to hold averaged data points for some weeks, a third for holding averaged data points for some months ...)
    * the number of data points to be stored in each rra
    * some header space


If you omit consolidation (that is: averaging out some data points), you won't “loose data”. But you will loose space!
Example: Store data every 300 seconds for a whole year. This leads to 12 (data points each hour) * 24 (hours per day) * 365 (days per year) data point (= 105120). Each data point holds 8 bytes, so the whole rrd will occupy about 840,960 Bytes (plus some header space) for each single data source. 

This may help estimating the size. At a glance, this would be VERY big may maybe slow, if used for lots of rrds.
Reinhard